Helminth Parasites of the Edible Dormouse (Glis glis) at Its Southern Distribution Limit in Northeastern Spain

Parasites are an important but frequently overlooked component of biodiversity. We investigated the helminth fauna of the edible dormouse (Glis glis) at the southern limit of its Iberian distribution to assess parasite diversity and compare populations from different protected areas.

Fecal samples collected between 2016 and 2018 were examined using non-invasive coprological methods. Samples originated from Montseny Natural Park, Montnegre and the Corredor Natural Park, and Guilleries-Savassona Natural Area. Parasite prevalence was compared among localities, host sex, sampling year, and sample origin.

Two host-specific helminths were detected: Paraheligmonina gracilis and Hymenolepis myoxi. P. gracilis was recorded in Montseny and Guilleries-Savassona, whereas H. myoxi was detected only once in a mixed infection. No helminths were detected in samples from Montnegre. Parasite prevalence did not differ significantly among years or between sexes but was significantly higher in fresh fecal samples than in nest-box samples.

The absence of host-specific helminths in the southernmost population, despite their occurrence in nearby populations and previous records across the Western Palearctic, suggests a possible local loss of parasite diversity associated with reduced host populations or environmental change. These findings highlight the importance of including parasite biodiversity in wildlife conservation and demonstrate the usefulness of non-invasive coprological surveys for monitoring threatened mammal populations.